1. Technical Field
The present invention relates to an optical fiber connector using a precise ferrule.
2. Related Art Statement
There are a number of known optical fiber connectors available in the market using precise ferrule made of stainless steel or fine ceramics. Also a considerable number of patent applications related thereto had been filed.
In brief, such known optical fiber connectors have construction generally as shown in FIG. 7. Such known construction comprises an optical fiber 20 fixed at the center of ferrule 30, which is housed in a connector sleeve 40 being axially movable and a compressive spring 50 is arranged between the bottom of the connector sleeve 40 and the ferrule 30.
The ferrule 30 is in general column shape and the connector sleeve 40 is in general cylindrical shape.
FIG. 7 and other figures show the connector just schematically and parts not relating to the present invention are omitted and the size of various parts may be exaggerated to give an easy understanding of the invention.
The establishment of connection in the known optical fiber connectors will be explained by referring to FIG. 8.
(i) As can be seen from FIG. 8a, top of ferrules 30A and 30B respectively of right and left connectors 10A and 10B are abutted together in an adaptor 60.
(ii) Then connector sleeves 40A and 40B are pushed to come together by a distance d by depressing the springs 50A and 50B and the end surfaces of the both ferrules 30A and 30B are joined together by the restoring force of the springs 50A and 50B.
Jointing between the connector sleeves 40A and 40B and the adaptor 60 is effected by a bayonet coupling, a screw coupling and other jointing means.
In the optical fiber connectors 10A and 10B having the above explained constructions, when the optical fiber cord 20A of the right hand connector 10A is pulled, the following situation results.
(1) As can be seen from FIG. 9a, the ferrule 30A comes backward while depressing the spring 50A. The ferrule 30B of the opposite side connector 10B follows this movement and comes forward in a distance corresponding to the backward movement of the ferrule 30A. (forward direction and backward direction are shown in the drawing)
(2) In this case, the ferrule 30B can only move forward direction in a distance corresponding to the amount of constriction of the spring 50B.
(3) By this reason, as shown in FIG. 9a, in which the ferrule 30A comes backward by a distance d from the coupling condition, i.e. as shown in FIG. 8b, there will be no gap between the abutting surfaces of the ferrules 30A and 30B.
In this case, the amount of constriction of the spring 50A becomes 2d by adding the amount d at the time of coupling plus amount d caused by the backward movement of ferrule 30A.
(4) However, if the ferrule 30A comes further backward as shown in FIG. 9b, the opposite ferrule 30B can not follow the backward movement and a clearance 32 is caused at the abutting end surfaces.
Namely the optical connection is substantially interrupted.